Using 100% embryo implantation IVF cycles to identify preferred embryo development patterns—morphokinetics

Abstract

Objective: Eliminating multiple gestations from assisted reproduction requires performing single embryo transfers (ET). This rests on the pre-transfer selection of a single, developmentally competent embryo from the cohort of available embryos. Primary methods for assessing embryo competence have not clarified the dynamic relationship between patterns of embryo development (morphokinetics) and the odds of implantation. We used cycles resulting in 100% embryo implantation to identify preferred morphokinetic patterns that predict favorable IVF-ET outcomes. Design: University based retrospective cohort study conducted from 1/01/02–11/30/02. Materials and Methods: Individual embryo culture allowed daily evaluation of embryos. Morphokinetic patterns were assigned based upon blastomere number and cell symmetry observed at 48 and 72 hours post retrieval. 100% embryo implantation was defined by sonographic confirmation that embryonic sac number equaled the number of embryos returned. The most common (Preferred) morphokinetic patterns resulting in 100% implantation were used to screen all fresh, non-donor ET cycles performed during the study period and analyzed for an association with cycle outcome. Statistical analysis was carried out using χ2 with p < 0.05 considered statistically significant. Results: Forty-five cycles (96 embryos) resulted in 100% implantation. These 96 embryos displayed 36 morphokinetic patterns. 5 Preferred morphokinetic patterns described 53.1% of the implanted embryos (Table 1). Considering the ET cycles that did not display 100% implantation, cohorts containing at least 1 embryo with 1 of the 5 Preferred morphokinetic patterns had significantly higher pregnancy and implantation rates regardless of whether the embryo exhibiting this pattern was transferred (Table 2). Table 1Description of Preferred morphokinetic patternsTable 2IVF-ET outcome according to embryo disposition and embryo availability of Preferred morphokinetic patternTable 2IVF-ET outcome according to embryo disposition and embryo availability of Preferred morphokinetic patterna p < 0.002 when compared to all other groups. b p < 0.04 when compared to all other groups. a p < 0.002 when compared to all other groups. b p < 0.04 when compared to all other groups. Conclusion: By analyzing embryo morphokinetic patterns in 100% implantation cycles, we identified 5 Preferred embryo development patterns. Screening all ET cycles for Preferred patterns suggests that they can aid in prognostication. Non-invasive morphokinetic assessment provides the opportunity to identify developmentally competent embryos and thereby designate cycles for single ET. This may aid in maintaining IVF-ET pregnancy rates and curtail multiple pregnancy outcomes.